SEOUL, Feb. 10 (Yonhap) -- North Korea's surprise proposal for an inter-Korean summit will pave the way for a dramatic advancement in bilateral ties, but its prospects hinge on future progress in the nuclear stand-off and an improvement in relations with the United States, experts said.

The presidential office announced Saturday that North Korea leader Kim Jong-un invited President Moon Jae-in to visit Pyongyang at an early date. The message was delivered by Kim's sister, Kim Yo-jong, during a meeting with Moon at Cheong Wa Dae.

Moon was quoted as responding, "Let us make it happen by creating the necessary conditions in the future."

Analysts said the proposal itself can be considered a "breakthrough," heralding the restoration of top-level communication channels to reduce cross-border tensions and improve relations.

But it remains unclear whether the highest-level rapprochement between the Koreas could secure support from other crucial stakeholders, namely the United States and Japan, they added.

They are skeptical of the North's current peace offensive and ruled out any dialogue with the North unless it would meaningfully contribute to making Pyongyang give up its nuclear and missile aspirations.

"Of course, there will be a long way to go before realizing denuclearization but we can say that the invitation could herald possibly opening of a channel for dialogue between the two leaders," Park Jeong-jin, vice director of the Institute for Far Eastern Studies, said. "It is encouraging in that we could have a channel that could be used for talks on denuclearization."

A reconciliatory mood has dramatically formed since North Korean leader Kim offered an olive branch to the South in his New Year speech, saying that he is willing to discuss the North's participation in the PyeongChang Winter Olympics.

The two Koreas held a series of high-ranking and working-level talks on the matter, which came after years of hiatus caused by the North's continued missile and nuclear provocations.

Based on their agreements, the North has sent hundreds of its athletes, cheerleaders, an art troupe and staffers to the games, which kicked off on Friday in the South's eastern town of PyeongChang.

Rapprochement culminated when the whole world watched South and North Korean athletes jointly marching at the opening ceremony of the Games on Friday. It was also attended by a North Korean delegation, including its titular leader Kim Yong-nam and Kim Yo-jong, the younger sister of the North Korean leader as a delegate.

Yang Moo-jin, a professor at the University of North Korean Studies, said that the visit by the North Korean leader's sister for the opening ceremony can be seen as a "symbolic" gesture that signals Pyongyang's wiliness to improve ties with the South.

"We can say that the North went all-in last year to complete its nuclear armament, now it seems to be moving toward to make efforts to improve inter-Korean relations," he said.

South Korea appears to have taken all measures in its power to make the North join in the Olympics. In early January, it agreed with the U.S. to suspend their planned joint military drills. They have also coordinated in exempting the North from multilayered sanctions to expedite its participation in the sporting event.

The Moon government is hoping that improved inter-Korean relations could pave the way for talks between Pyongyang and Washington on the former's denuclearization.

The hope, however, has been met with skepticism, especially from hardliners.

Critics worry that the North's peace offensive is aimed at driving a wedge between the allies and weakening the global sanctions regime they say has been a key part in nudging the North toward dialogue with the South.

The biggest challenge is the skepticism being voiced in the U.S., which seems incredulous that the North has any intention of giving up its nuclear weapons. The North has said that denuclearization will never be on negotiation table.

The skepticism was highlighted when U.S. Vice President Mike Pence on Friday urged Pyongyang to "permanently" abandon its nuclear aspirations, saying, "We don't want to repeat the mistakes of the past."

"We don't want to repeat the mistakes of the past. President Moon and I reflected on that last night. And that denuclearization has to be the starting point of any change, not the end point of any change," Pence said. He was in South Korea to attend the opening ceremony of the Olympics.

Experts said what is vitally important now is how the Seoul government can engineer cooperation from the U.S. and other relevant partners and get them on board in efforts to keep the peaceful mood going.

"The North has invited our president to Pyongyang but there have been no signal whatsoever about its changed stance on the nuclear issue," Woo Jung-yeop, a researcher at the Sejong Institute, said.

"Our government needs evidence showing that the North has changed its stance on the denuclearization matter when it meets with the U.S. and discuss the recent development." he said. "Under current circumstances, it seems to be tough to expect a marked turnaround in North Korea-U.S. relations."

Yet another challenge lurking ahead might come when Seoul and Washington conduct their postponed military drills, which could be used as an excuse by the North to walk away from any talks. Reports have it that they will likely hold the military exercises in mid-April.

"To scale down or do anything about the military drills, there should be something we can provide to support it in meetings with the U.S." Woo said. "I'm still doubtful about it."